Pregnancy Nutrition Calculator
Estimate daily protein, iron, folate, and calcium requirements during pregnancy based on your weight, trimester, age, and whether you are carrying multiples. Ideal for building a trimester-specific meal plan.
Last updated: September 2026
Formula below · 3 sources (dietaryguidelines.gov, acog.org, mayoclinic.org) · Updated Sep 2026
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About this calculator
Nutritional needs increase significantly during pregnancy and shift by trimester. This calculator converts pre-pregnancy weight from lbs to kg (weightKg = lbs ÷ 2.205), then computes each nutrient. The targets follow the Institute of Medicine Dietary Reference Intakes for pregnancy. Protein (g/day) = 0.8 g/kg in the first trimester and 1.1 g/kg from week 14, using pre-pregnancy weight; vegans get 20% more to allow for lower plant-protein digestibility, and about 25 g/day is added for each additional baby. Iron = 27 mg/day in every trimester (49 mg for vegetarians and vegans, as the IOM sets vegetarian iron needs 1.8× higher). Folate = 600 mcg DFE/day throughout. Calcium = 1,000 mg/day (1,300 mg if under 19). For twins or triplets, ask your provider about iron and folate, as no separate DRI exists. The result lists each target rather than combining them into a score, since different nutrients cannot be meaningfully added together. A registered dietitian can help translate these numbers into a personalised meal plan.
How to use
Example: 28-year-old woman, 140 lbs, week 20, singleton pregnancy, no dietary restrictions. weightKg = 140 ÷ 2.205 ≈ 63.5 kg. Trimester = 2. Protein = 63.5 × 1.1 ≈ 70 g. Iron = 27 mg. Folate = 600 mcg DFE. Calcium = 1,000 mg. Result: "Protein 70 g; iron 27 mg; folate 600 mcg DFE; calcium 1,000 mg per day". Use these individual nutrient figures to assess your daily diet against recommended intake levels.
Frequently asked questions
How does protein requirement change during each trimester of pregnancy?
In the first trimester, protein needs are similar to pre-pregnancy levels, based on body weight at roughly 1.1 g per kg. From the second trimester onward, an additional 25 g per day is recommended to support fetal tissue growth. If you are carrying twins or more, these values are multiplied further. Vegans and vegetarians are advised to increase protein intake by about 20% because plant proteins are less bioavailable than animal proteins.
Why do pregnant women need more folate and iron during pregnancy?
Folate (vitamin B9) is critical for neural tube formation, especially in the first trimester, and requirements rise to 600–800 mcg/day during pregnancy compared to 400 mcg normally. Iron needs nearly double to around 27 mg/day because your blood volume expands by up to 50% and iron is required for fetal red blood cell production. Deficiencies in either nutrient are linked to serious complications including neural tube defects and anaemia. Many prenatal vitamins are formulated specifically to cover these increased needs.
Do nutritional needs differ when carrying twins or multiples during pregnancy?
Yes, significantly. When carrying twins, most nutrient targets are multiplied by approximately 1.5, and for triplets by 2. Caloric needs also increase by an additional 300 calories per extra fetus beyond the standard +300 kcal/day for a singleton pregnancy. Iron and folate requirements are particularly important to monitor in multiple pregnancies due to higher risks of anaemia and premature birth. Always work with a maternal-fetal medicine specialist or registered dietitian for a personalised plan.